Duplex Ultrasound Duplex Ultrasound Assessment of the Assessment of the

Venous SystemVenous System

David JenkinsPhlebologist

Sydney

• Seize the opportunity

• Ask ANY questions - you will be doing many others present a favour!

• Be involved – don’t go home disappointed that you could have learned more

What you should achieve in this What you should achieve in this session:session:

• Understand the basic principles involved in production of an ultrasound image

• Practical hands-on experience to become familiar with duplex technology

Overview:Overview:

Replaced venography as the “gold standard”

• High specificity• High sensitivity• Non-invasive• Accessible• Cost effective

Hand held Doppler:

• Used clinically for ~ 25yrs• Relatively poor sensitivity (30% to 50% of reflux

missed)1,2

• Poor specificity (auditory signal only, not anatomically precise)

• Cheap

Doppler Shift

ft 2 ucosfd = ________

c

ft is transmitted frequency = angle source motion and direction of receiver u = source velocity C = velocity of sound

Transducer piezoelectric crystals

Wavefront

Reflection

Refraction

Absorption

Ultrasonic display:

A mode (amplitude)M mode (movement) - cardiac ultrasound B mode (brightness) - grey-scale imagingDUPLEXTRIPLEXSpectral DisplayColour Flow DopplerPower Doppler

Spectral trace

How to hold the transducer:

Picture moves opposite direction to hand

Arteries are red, veins are blue

Right angle to skin (or area of interest)

Toe and heel

Resolution

Axial reverberation echoes

Steering & Focusing Pulsed Doppler

Lateral resolution

Duplex Sonography:Duplex Sonography:

Duplex Sonography:Duplex Sonography:

Diagnosis with duplex

PVD DVT CVI Baker’s cyst Haematoma, gastroc tear Aneurysm, pseudoaneurysm Lymph nodes

Duplex Sonography:Duplex Sonography:

Normal venous flow:

Spontaneous Phasic Non-pulsatile Cephalad Augmentable

Duplex Sonography:Duplex Sonography:

Normal venous flow:

Lumen is hypoechoic, compressible, diameter changes with respiration

Vein wall is thin, regular and smooth Valves appear as localised dilatations, the cusps

are thin and project obliquely. Cusps move with respiration and can be seen to approximate

Duplex Sonography:Duplex Sonography:Reflux:

Valves close due to retrograde flow – gravity, compression and Valsalva

Flow rate ~ 30m/sec required for valve closure No consensus as to what degree of reflux is

physiological Pathological reflux > ½ sec Volume and duration of reflux variable

Duplex Sonography:Duplex Sonography:

Reflux:

Assess vein in saggital plane (transverse for compressibility)

SV for PW should be 25-50% of lumen Inspect entire length of vein – not simply SFJ &

SPJ Allow time for refilling Poor augmentation may be due to obstruction Make a hard copy of spectral analysis

Mapping:Mapping:

“One picture paints ten thousand words” F Barnard (1927)

Accurate mapping is critical for good management and follow up

Concise information that is easily interpreted Needs to contain all information necessary to

write report

Deep Vein ThrombosisDeep Vein Thrombosis

B mode: Incomplete compression Echogenic clot visible Vein distended by thrombus Loss of phasic flowColour: Filling defect Distention Absence of flow

Deep Vein ThrombosisDeep Vein ThrombosisPitfalls in diagnosis:

Acute thrombus may be sonolucent Subacute thrombus may not distend wall Partial thrombus may not interfere with

Valsalva/augmentation Valsalva’s only works above the knee

Deep Vein ThrombosisDeep Vein Thrombosis

Chronic DVT: Reduced venous diameter / occlusion Thickened irregular vein walls Echogenicweblike filling defects Absence of acute DVT Coexistent deep venous insufficiency Presence of collateral vessels

THE ENDTHE END

BooksBooks: :

Zwiebel,WJ Introduction to VascularZwiebel,WJ Introduction to VascularSonographySonographyISBN 0ISBN 0--72167216--69496949--22

HennericiHennerici,M. ,M. Vascular Diagnosis Vascular Diagnosis With Ultrasound With Ultrasound ISBN 3ISBN 3--1313--103103--83148314